1. Field of the Invention
The present invention relates to a panel loading method for loading an inner panel to an outer panel and a panel-loading support device.
2. Description of the Related Art
A method for loading a workpiece to a hemming machine disclosed in Japanese Patent No. 3634149 employs a plurality of grippers 821, 822 and 823 suspended from a robot hand 81. The grippers 821, 822 and 823 grip bent peripheries WOe of a plurality of circumferential sides of outer members WRO and WLO to load workpieces WR and WL onto the hemming machine. Specifically, each of the grippers 821, 822 and 823 has a pair of gripper claws 82b and 82c, one of the gripper claws 82b and 82c having a projection 82d and the other of the gripper claws 82b and 82c having a recess 82e. The bent peripheries WOe of the outer members WRO and WLO are gripped between the projection 82d and the recess 82e to be partially deformed. When the bent peripheries WOe of respective sides WOa, WOc and WOd of the outer members WRO and WLO are gripped by the grippers 821, 822 and 823, the (inner) gripper claw 82b also serves as a workpiece retainer for preventing the uplift of the inner members WRI and WLI, thereby preventing misalignment of the inner members WRI and WLI relative to the outer members WRO and WLO in loading the workpiece onto the hemming machine. After loading the workpiece, the workpiece is hemmed.
Though the workpiece is loaded after the outer panel and the inner panel are overlapped, when a parting line of the panel comes to a side orthogonal to a loading direction as shown in FIG. 17, a bent portion (hemming flange) 104 that is bent at the periphery of the outer panel 100 interferes with an end of the inner panel 102 in the setting path of the inner panel 102 when the outer panel 100 and the inner panel 102 are overlapped.
In order to avoid such an interference, an end of the inner panel 102 are cut off as shown in FIG. 18 or the outer panel 100 are pulled and stretched by a sucker 106.
However, when an end of the inner panel 102 is cut off, an engagement length for hemming is reduced, so that fastening strength and, consequently, the accuracy and rigidity of the hemming are reduced. Specifically, since the outer panel 100 are folded back to hold the inner panel 102 to fasten the plate members during the hemming, when an end of the inner panel 102 is cut off, the fastening strength is lowered to cause a misalignment of the inner panel 102 and the outer panel 100, resulting in decrease in the processing accuracy. When the outer panel 100 is pulled by a sucker, the outer panel 100 may not be sufficiently stretched depending on the shape and rigidity of the outer panel 100. The technique disclosed in the above Japanese Patent No. 3634149 does not overcome the above deficiencies.